Brittle failure of components weakened by cracks or sharp and blunt V-notches is a topic of active and continuous research. It is attractive for all researchers who face the problem of fracture of materials under different loading conditions and deals with a large number of applications in different engineering fields, not only with the mechanical one. This topic is significant in all the cases where intrinsic defects of the material or geometrical discontinuities give rise to localized stress concentration which, in brittle materials, may generate a crack leading to catastrophic failure or to a shortening of the assessed structural life. Whereas cracks are viewed as unpleasant entities in most engineering materials, U- and V-notches of different acuities are sometimes deliberately introduced in design and manufacturing of structural components. Dealing with brittle failure of notched components and summarizing some recent experimental results reported in the literature, the main aim of the present contribution is to present a review of some local approaches applicable near stress raisers both sharp and blunt. The reviewed criteria allowed the present authors to develop a new approach based on the volume strain energy density (SED), which has been recently applied to assess the brittle failure of a large number of materials. The main features of the SED approach are outlined in the paper and its peculiarities and advantages accurately underlined. Some examples of applications are reported, as well. The present review is based on the authors’ experience over more than 15 years and the contents of their personal library. It is not a dispassionate literature survey.

Recent developments in brittle and quasi-brittle failure assessment of engineering materials by means of local approaches

Thank you for downloading some basic problems of the mathematical theory of elasticity. As you may know, people have search hundreds times for their favorite readings like this some basic problems of the mathematical theory of elasticity, but end up in infectious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they cope with some infectious bugs inside their computer.

Some Basic Problems Of The Mathematical Theory Of Elasticity

In contrast to animal and fungal cells, green plant cells contain one or multiple chloroplasts, the organelle(s) in which photosynthetic reactions take place. Chloroplasts are believed to have originated from an endosymbiotic event and contain DNA that codes for some of their proteins. Most chloroplast proteins are encoded by the nuclear genome and imported with the help of sorting signals that are intrinsic parts of the polypeptides. Here, we show that a chloroplast-located protein in higher plants takes an alternative route through the secretory pathway, and becomes N-glycosylated before entering the chloroplast.

Evidence for a protein transported through the secretory pathway en route to the higher plant chloroplast.

A control studio object system is disclosed which allows a process control environment to be easily and quickly configured or modified. The control studio object system includes a stencil portion having stencil items conforming to algorithms and a diagram portion to which the stencil items may be copied via a drag and drop operation. Because the stencil items are objects which contain all of the information required by a diagram portion to create an object that contains all of the information necessary to program the process control environment, the completed diagram portion reflects the actual configuration of the process control environment. Additionally, providing the stencil items as objects allows the diagrammed environment to be installed directly to nodes without requiring the diagram to be compiled or rewritten in a language conforming to the node.

System for configuring a process control environment

Quality-guided phase unwrapping is a widely used technique with different quality definitions and guiding strategies reported. It is thus necessary to do a detailed comparison of these approaches to choose the optimal quality map and guiding strategy. For quality maps, in the presence of noise, transform-based methods are found to be the best choice. However in the presence of discontinuities, phase unwrapping is itself unresolved and hence quality-guided phase unwrapping is not sufficient. For guiding strategies, classical, two-section, and stack-chain guiding strategies are chosen for comparison. If accuracy is the foremost criterion then the classical guiding strategy with a data structure of indexed interwoven linked list is best. If speed is of essence then the stack-chain guiding strategy is the one to use.

Quality-guided phase unwrapping technique: comparison of quality maps and guiding strategies

Finite element simulation of isoclinic and isochromatic phasemaps for use in digital photoelasticity

Engineering Fracture Mechanics

New Boundary Information Encoding and Autoseeding for Effective Phase Unwrapping of Specimens with Cutouts

Stress freezing in photoelasticity is regularly employed for 3-D elastic stress analysis of geometrically complex models, wherein the models under load are soaked at the stress freezing temperature and slowly cooled to room temperature. During this process, a model may distort or fail undergoing large deformations at the stress freezing temperature owing to thermo-mechanical interactions. The contribution of thermal deformation to the model distortions is neglected in the available literature of stress freezing. This aspect of stress freezing is investigated in this paper, wherein Digital Image Correlation (DIC) is used to study the strain behavior during a complete stress freezing cycle for an epoxy made of CY230 resin cured with HY951 hardener. The results show that the thermal contributions to the model distortions at the critical temperature must be taken care of to estimate the failure margins. The distortions and failures would mainly depend upon the thermal and mechanical response of the model material and the complexity of the model.

A Revisit to the Frozen Stress Phenomena in Photoelasticity

An optical arrangement for application of the phaseshifting technique to reflection photoelasticity is presented. The intensity equations for application of phaseshifting methodology are obtained by Jones' calculus. A new portable reflection polariscope is designed to effect the optical arrangement. The use of a commercially available Handycam is shown to meet the requirement of image capturing for digital photoelastic analysis. Fringe order variations for three arbitrary lines in a circular disc under diametral compression are obtained by the new methodology and compared with theoretical predictions. The comparison is found to be good.

K. Ramesh

Papers

Finite element simulation of isoclinic and isochromatic phasemaps for use in digital photoelasticity

Engineering Fracture Mechanics

New Boundary Information Encoding and Autoseeding for Effective Phase Unwrapping of Specimens with Cutouts

A Revisit to the Frozen Stress Phenomena in Photoelasticity

Automation of data acquisition in reflection photoelasticity by phaseshifting methodology